Addressing the Challenges in the Placement of Seafloor Infrastructure on the East Breaks Slide-A Case Study: The Falcon Field (EB 579/623), Northwestern Gulf of Mexico

Abstract

The East Breaks Slide is a late Pleistocene shelf-slope instability feature that has impacted some 342-square miles in the western portion of the East Breaks Federal lease area (EB) in the northwestern Gulf of Mexico. However relict this slide may be it has a significant impact on the present seafloor displaying irregular, tilted, and rotated blocks of intact stratigraphy within an amorphous and disturbed slump matrix. The Falcon Field is near the center of the western lobe of the slide in EB 579 and 623. One of the challenges faced by the operators was to locate a feasible pipeline route from the Falcon Field to the host platform in Mustang Island Block A-103. The rough topography over the East Breaks Slide restricted a direct route from the field to the host platform. An irregular seafloor and potential slope instability were two factors that had to be addressed for selecting a pipeline route, and at the same time, keeping the route as short as possible. Both factors could have a significant impact on the potential for spanning of the pipeline and stability of the bottomfounded man-made infrastructure planned.Pre-survey route planning was undertaken using public bathymetric data and proprietary 3D seismic data. A digital terrain model (dtm) of the seafloor was developed from which potential routes were viewed and cross-sections cut to determine if pipe span would be an issue. Changes and alternative considerations to the routing could be done using these data sets to investigate multiple route scenarios.The Falcon Team had a promising route selected before any high-resolution field survey was commissioned and little change to the routing was necessary. The field work was planned with a contingency of altering the route within the slide if the planned route was not feasible based on the survey. Minor alterations were made to the route within the slide, but the survey corridor was adequately planned through the slide feature to accommodate the changes. Once the route was determined a routine hazards assessment report was completed and issued to satisfy Minerals Management Service requirements.

New classification system for mass transport complexes in offshore Trinidad

“…In addition, their influence in the shaping of seafloor bathymetry and continental margin architecture is well documented (Norem et al , 1990; Masson et al , 1998; Gee et al , 1999, 2001, 2006; Frey‐Martinez et al , 2005; Moscardelli et al , 2006). The sometimes catastrophic, erosive nature of MTC deposits represents a potential geotechnical hazard for offshore infrastructures owing to their ability to compromise the integrity of underwater equipment such as cables, communication lines and pipelines (Hoffman et al , 2004; Shipp et al , 2004). It is also well known that a sudden displacement of the seafloor through catastrophic slumping or sliding can potentially disrupt the water column above the failure and generate tsunamigenic waves that can affect coastal areas (Pelinovsky & Poplavsky, 1996; Nisbet & Piper, 1998; Dawson et al , 2004; Fryer et al , 2004).…”

Mass-transport complexes and associated processes in the offshore area of Trinidad and Venezuela

“…In some settings, up to 70% of the entire slope and deepwater stratigraphic column is composed of MTCs and associated deposits (Maslin et al, 2004;Newton et al, 2004). The prevalence of mass failures represents a significant threat to the security of continental slope and deep-marine engineered installations (Hoffman et al, 2004;Pirmez et al, 2004;Shipp et al, 2004). Such dangers can have a significant impact on the financial aspects of hydrocarbon exploration and development in deep-water locations.…”

“…Likewise, destabilization of pressure and temperature regimes by changing water temperatures, shifting ocean currents, or lowering sea level can cause melting of frozen clathrates and initiate failures along marine margins. These episodes of catastrophic mobilization of huge amounts of slope sediments represent a risk for submarine installations, such as pipelines and communication lines (Hoffman et al, 2004), and also have the potential to generate tsunamis, a phenomenon that represents a significant hazard for coastal communities and nearshore navigation (Nisbet and Piper, 1998;Hearne et al, 2003;O'Loughlin and Lander, 2003).…”

Middle Ordovician mass‐transport deposits from western Inner Mongolia, China: Mechanisms and implications for basin evolution

“…Submarine gravity‐induced deposits, such as slides, slumps and debrites, also known as mass‐transport deposits (MTDs), represent important components of modern and ancient deep‐water stratigraphic successions (Dott, 1963; Nardin et al ., 1979; Moscardelli & Wood, 2015; Cardona et al ., 2020). They are of great significance because they shape the sea floor, record climatic and tectonic signals, and represent potential catastrophic hazards for human activities (Pelinovsky & Poplavsky, 1996; Hoffman et al ., 2004; Shipp & Nott, 2004; Frey‐Martínez & Cartwright, 2005; Moscardelli & Wood, 2006). Mass‐transport events can be triggered by many processes that cause shear stress to exceed the shear strength within the sediment pile leading to downslope movement (Lewis, 1971; Coleman & Prior, 1988; Handford & Loucks, 1993).…”